JP2015116085A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such the problem that a driver tends to feel discomfort with the slowdown due to power generation by an alternator during inertia travelling.SOLUTION: A vehicle control device includes: a step S100 of deciding a target value of deceleration by the alternator during inertia travelling of a vehicle based on a velocity of the vehicle; and step S200 to S400 for bringing the deceleration by the alternator closer to the decided target value after the step S100.

Description

  The present invention relates to vehicle control.

  Automobiles usually have an alternator that generates electricity. Alternator power generation is performed using engine torque and vehicle inertia. In order to improve fuel efficiency, it is effective to appropriately perform power generation using the inertia (kinetic energy) of the automobile and regenerate the inertia of the vehicle as electric power. Thus, when power generation is performed using inertia, the vehicle decelerates.

  In power generation using the inertia of an automobile, a method of controlling an alternator so as to generate a negative torque corresponding to a difference between a current deceleration and a target deceleration is known. The calculation of the target deceleration is executed based on the current deceleration, the throttle opening, etc. (for example, Patent Document 1).

JP 2010-288343 A

  The problem of the above prior art is that the driver tends to feel uncomfortable during inertial driving. Inertia travel refers to travel in a state where neither the accelerator pedal nor the brake pedal is depressed. The driver may feel uncomfortable if the deceleration is too strong during inertial driving and may step on the accelerator pedal. When the accelerator pedal is stepped on, the fuel consumption is worse than in the case of coasting. On the other hand, if the deceleration is too weak during coasting, the driver may feel idle. In addition, downsizing of the apparatus, cost reduction, resource saving, ease of manufacture, improvement in usability, and the like have been desired.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a vehicle control device is provided. The vehicle control device determines a target value for deceleration when the vehicle is coasting according to a vehicle speed that is the speed of the vehicle. A target deceleration determination unit; and a deceleration control unit that executes deceleration control to bring the deceleration closer to the determined target value by controlling the regeneration device when the vehicle is coasting. Prepare. According to this aspect, the uncomfortable feeling caused by deceleration during inertial running is reduced. This uncomfortable feeling is considered to change depending on the vehicle speed. Therefore, it is possible to reduce the uncomfortable feeling by controlling the deceleration based on the vehicle speed.

(2) In the above aspect, it may be determined that the vehicle is coasting when both an accelerator pedal and a brake pedal provided on the vehicle are not depressed. According to this form, it can be easily determined whether the vehicle is coasting.

(3) In the above aspect, the target deceleration determining unit acquires the allowable deceleration according to the vehicle speed by referring to a predetermined relationship between the allowable deceleration and the vehicle speed, and the acquired allowable A deceleration may be determined as the target deceleration. According to this aspect, it is possible to determine a target deceleration that can reduce the sense of incongruity without performing calculation or the like each time. The allowable deceleration is a deceleration value determined within a range in which the driver does not feel uncomfortable.

(4) In the above aspect, the regenerative device is an alternator, and may be connected to a rotating shaft of an engine mounted on the vehicle. According to this aspect, the above control can be realized by using an existing hardware configuration.

(5) In the above aspect, the deceleration control unit; sets a target value of a negative torque generated by regeneration of the alternator, a rotational speed of an engine mounted on the vehicle, a vehicle weight of the vehicle, and the vehicle speed. A target negative torque determination unit that determines in consideration of at least one of the above; and an alternator control unit that brings the negative torque closer to the determined target value as control of the regenerative device. According to this aspect, the deceleration control using the alternator can be appropriately executed.

(6) In the above aspect, the alternator control unit may bring the negative torque closer to the determined target value by controlling the excitation current flowing through the alternator based on the target value of the negative torque. According to this aspect, the negative torque of the alternator can be appropriately controlled according to the characteristics of the alternator.

(7) In the above aspect, the alternator control unit may set an upper limit value of the excitation current as the excitation current control. According to this aspect, it is possible to perform control suitable for the characteristics of the alternator while avoiding the occurrence of a large deceleration that causes a sense of incongruity.

(8) In the above aspect, the target deceleration determination unit may determine the target value so as to monotonously increase with respect to the increase in the vehicle speed in at least a partial range of the vehicle speed. According to this aspect, braking of the vehicle becomes more appropriate. This is because at least in some speed ranges, when the speed is high, the vehicle decelerates with a larger deceleration.

(9) In the above aspect, the deceleration control unit may reduce the deceleration with respect to time when the deceleration is decreased in at least a portion of the vehicle speed. The deceleration control may be executed so that the absolute value of the rate at which the deceleration changes increases. According to this aspect, when the deceleration is decreased, the deceleration is easily brought close to the target value. The target value for deceleration increases monotonically with increase in speed in at least a part of the speed range, and therefore decreases with deceleration. Therefore, when the deceleration is decreased, it becomes easier to approach the target value by increasing the absolute value of the rate at which the deceleration changes than when increasing the deceleration.

(10) In the above aspect, the target deceleration determination unit is configured so that the change rate of the deceleration with respect to the vehicle speed monotonously decreases with respect to the increase in the vehicle speed in at least a part of the vehicle speed. The value may be determined. According to this embodiment, the uncomfortable feeling is further reduced. If the rate of change of the target value decreases monotonously with increase in speed, the target value can be avoided from changing suddenly, so that the above effect can be obtained.

(11) In the above aspect, the deceleration control unit may determine a rate of change of the deceleration with respect to time according to the vehicle speed, and execute the deceleration control based on the determined rate of change. According to this aspect, it becomes easy to realize the deceleration control that further reduces the uncomfortable feeling.

  The present invention can be realized in various forms other than the above. For example, the present invention can be realized in the form of a deceleration control method, a program for realizing the control method, a non-temporary storage medium storing the program, and the like.

The block diagram which shows the component related to the deceleration control process. The flowchart which shows deceleration control processing. The graph which illustrates the relationship between the whole allowable deceleration, the allowable deceleration, and the vehicle speed. The graph which illustrates the relationship between the actual deceleration and time in the case of accelerator-off. The graph which illustrates the relationship between the actual deceleration and time in the case of brake-off. The graph which illustrates the relationship between permissible deceleration and vehicle speed (modifications 1 and 2). The graph which illustrates the relationship between the change rate of the actual deceleration with respect to a vehicle speed, and a vehicle speed (modification 3). The graph which illustrates the relationship between the change rate of the actual deceleration with respect to a vehicle speed, and a vehicle speed (modification 4). The graph which illustrates the relationship between the change rate of the actual deceleration with respect to a vehicle speed, and a vehicle speed (modification 5).

  FIG. 1 is a block diagram showing components related to a deceleration control process to be described later among the components of a four-wheeled vehicle. FIG. 1 shows an engine ECU 30, an alternator 40, a belt 45, a battery 50, an engine 60, a transmission 70, a drive shaft 75, drive wheels 80, and a sensor group 90. Sensor group 90 includes an accelerator stroke sensor 91, a brake stroke sensor 92, a throttle sensor 93, a wheel speed sensor 94, a vehicle speed sensor 95, and a battery sensor 96.

  The engine ECU 30 inputs a control signal to the engine 60 according to the stroke amount (depression amount) of an accelerator pedal (not shown). Engine 60 is a well-known internal combustion engine, and generates torque in accordance with a control signal input from engine ECU 30. Torque generated by the engine 60 is transmitted to the drive wheels 80 via the transmission 70 and the drive shaft 75. The engine ECU 30 acquires values indicating the rotation speed and torque of the engine 60 from the engine 60.

  Torque generated by the engine 60 rotates a rotor (not shown) of the alternator 40 via the belt 45. The alternator 40 generates power by the rotation of the rotor. The rotor of the alternator 40 generates negative torque during power generation. Thus, since the power generation by the alternator 40 places a load on the engine 60, the rotational speed of the drive wheels 80 is reduced via the transmission 70, causing a reduction in the vehicle speed. The electric power generated by the alternator 40 is stored in the battery 50. The electric power stored in the battery 50 is supplied to an electronic device or the like mounted on the automobile.

  The power generation of the alternator 40 is executed according to the control of the engine ECU 30. Specifically, the engine ECU 30 determines the generated voltage and the limit value of the excitation current based on the rotational speed of the engine 60, the remaining capacity of the battery 50, and the like, and instructs the alternator 40. The alternator 40 performs power generation using the instructed power generation voltage. At this time, the alternator 40 performs control so that the exciting current that actually flows does not exceed the instructed limit value. This control is realized by a control circuit incorporated in the alternator 40. Alternator 40 inputs the values of the actual excitation current and generated voltage to engine ECU 30.

  The accelerator stroke sensor 91 measures the stroke amount of the accelerator pedal. The brake stroke sensor 92 measures the stroke amount of a brake pedal (not shown). The throttle sensor 93 measures the opening of a valve (not shown) for adjusting the intake air of the engine 60. The wheel speed sensor 94 acquires a pulse signal indicating the rotation period of the drive wheel 80 and measures the rotation speed of the drive wheel 80.

  The vehicle speed sensor 95 measures the traveling speed of the vehicle based on the measurement result by the wheel speed sensor 94, the position information by GPS, and the like. The battery sensor 96 estimates the remaining capacity of the battery 50 based on the terminal voltage value acquired from the battery 50. The measurement results obtained by the sensor group 90 described above are input to the engine ECU 30.

  FIG. 2 is a flowchart showing the deceleration control process. The deceleration control process is a process executed by the engine ECU, and is started when the stroke amounts of both the accelerator pedal and the brake pedal become zero (shift to inertial running). If the engine ECU 30 detects that the stroke amount of at least one of the accelerator pedal and the brake pedal is greater than zero after the start of the deceleration control process, the engine ECU 30 immediately ends the deceleration control process and performs normal control. Migrate to

First, a target deceleration is determined (step S100). The target deceleration is a target value for deceleration caused by the negative torque of the alternator 40. The deceleration is a value (m / s ² ) obtained by differentiating the vehicle speed, and takes a positive value when the vehicle is decelerating. The target deceleration is predetermined with respect to the vehicle speed, and the relationship is stored in the engine ECU 30.

  FIG. 3 is a graph illustrating the relationship between the overall allowable deceleration, the allowable deceleration, and the vehicle speed. The total allowable deceleration is the maximum value of deceleration at which the driver does not feel uncomfortable and is determined by a sensory test. The driver feels uncomfortable if the deceleration is too large after the shift to coasting. The overall allowable deceleration in the present embodiment is determined as a function of the vehicle speed based on the knowledge that it increases as the vehicle speed increases.

  As shown in FIG. 3, the curve T indicating the overall allowable deceleration in the present embodiment changes logarithmically. That is, the curve T is a monotonically increasing and upwardly convex curve, and the rate of change of the curve T decreases as the vehicle speed increases.

  A curve A in FIG. 3 shows an allowable deceleration by the alternator 40. The allowable deceleration is the maximum value that can be assigned to the deceleration by the alternator 40. The deceleration control process is executed during inertial running as described above. During coasting, it is preferable to increase the power generation amount by increasing the negative torque of the alternator 40 as much as possible. However, in addition to the negative torque of the alternator 40, the negative torque of the engine 60 and the road surface resistance of the drive wheels 80 cause the deceleration during inertial running. Therefore, a value obtained by subtracting the deceleration caused by other than the alternator 40 from the overall allowable deceleration is determined as the allowable deceleration by the alternator 40.

  As shown in FIG. 3, when the vehicle speed is Vm or less, the allowable deceleration is set to zero. This is because when the negative torque is generated by the alternator 40 when the vehicle speed is Vm or less, the possibility of causing an engine stall increases.

  The target deceleration set in step S100 is an allowable deceleration value determined from the current vehicle speed and the relationship shown in FIG.

Subsequently, a target negative torque is determined (step S200). The target negative torque is a negative torque value by the alternator 40 for realizing the allowable deceleration. The deceleration D by the alternator 40 is expressed by the following equation (1).
D = (Ta × NE) / (W × V) (1)
Ta is the negative torque (Nm) by the alternator 40, NE is the engine speed (r / s), W is the vehicle weight (kg), and V is the vehicle speed (m / s). Therefore, the negative torque by the alternator 40 is expressed by the following formula (2).
Ta = (D × W × V) / NE (2)

  The vehicle speed value obtained from the vehicle speed sensor 95, the target deceleration value is substituted for the deceleration D, the fixed value is set for the vehicle weight W, and the value obtained from the engine 60 is substituted for the engine speed NE. By doing so, the target negative torque Ta is calculated. The fixed value of the vehicle weight W is stored in the engine ECU 30.

  Next, a target limit value of the excitation current is determined (step S300). The excitation current target limit value is a value used in step S400 described later. This determination is executed by inputting the target negative torque calculated in step S200, the instructed power generation voltage, and the current engine speed into a map stored in advance.

  Subsequently, the value actually instructed as the excitation current limit value (hereinafter referred to as “instruction value”) is brought close to the target limit value determined in step S300 (step S400). Step S400 is executed over a predetermined time so that the indicated value changes smoothly from the current value.

  FIG. 4 is a graph illustrating the relationship between the actual deceleration by the alternator 40 (hereinafter referred to as “actual deceleration”) and time, and the stroke amount of the accelerator pedal has become zero (hereinafter referred to as “accelerator off”). ) When the deceleration control process is started.

  Time Ta1 is the time when step S400 was started. The target deceleration Da1 is a target deceleration corresponding to the time Ta1. Usually, when the accelerator is off, as shown in FIG. 4, the actual deceleration Dta1 at time Ta1 is smaller than the target deceleration Da1. However, this relationship is not always true when the accelerator is off. This is because the target deceleration in the present embodiment is determined according to the vehicle speed and is not determined according to the pedal operation. The same applies to the brake operation described later.

  In the case of the relationship illustrated in FIG. 4, the instruction value is increased in step S400 in order to bring the actual deceleration closer to the target deceleration. At this time, the indicated value is increased over a predetermined time so that the actual deceleration does not suddenly increase. As a result, the actual deceleration increases linearly at a predetermined rate of change, as shown in FIG.

  Next, it is determined whether the actual deceleration has converged to the target (step S500). Specifically, it is determined whether the actual deceleration is within a predetermined error (for example, ± 10%) with respect to the target deceleration. If the actual deceleration has converged to the target (step S500, YES), the deceleration control process ends. If the actual deceleration has not converged to the target (step S500, NO), steps S100 to S400 are repeated.

  The time Ta2 in FIG. 4 is the time when the second step S400 is started. Although the actual deceleration Dta2 at the time Ta2 has become larger than the actual deceleration Dta1 by the previous step S400, it is still smaller than the target deceleration Da2 at the time Ta2. Therefore, the instruction value is increased in step S400 so that the actual deceleration continues to increase. The target deceleration Da2 has a value smaller than the target deceleration Da1 based on the relationship shown in FIG. 3 because the vehicle speed decreases between time Ta1 and time Ta2.

  Also at time Ta3, the actual deceleration increases similarly to time Ta2. At the time Ta4, the actual deceleration becomes substantially the same value as the target deceleration Da4 and converges to the target. Therefore, the engine ECU 30 ends the deceleration control process, and thereafter controls the alternator 40 by normal control.

  FIG. 5 is a graph illustrating the relationship between actual deceleration and time when the deceleration control process is started when the stroke amount of the brake pedal becomes zero (hereinafter referred to as “brake off”).

  The time Tb1 is the time when the first step S400 is executed. At time Tb1, the actual deceleration Dtb1 is larger than the target deceleration Db1. Therefore, the engine ECU 30 smoothly reduces the instruction value so that the actual deceleration decreases.

  When the control for decreasing the actual deceleration is executed, the actual deceleration decreases with the passage of time, while the target deceleration also decreases with the passage of time. Therefore, in order to converge the actual deceleration to the target deceleration, the actual deceleration is reduced with a larger absolute value gradient than when the actual deceleration is increased.

  As shown in FIG. 5, the actual deceleration decreases at time Tb2 and Tb3 in the same manner as at time Tb1, and converges at time Tb4. The engine ECU 30 shifts to normal control after time Tb4.

  According to the embodiment described above, the uncomfortable feeling that the driver learns can be reduced. This is because, in the present embodiment, the target deceleration is changed according to the vehicle speed, and the actual deceleration is made closer to the target deceleration smoothly. According to such a method, for example, it is avoided that the deceleration is too large when the accelerator is off or the deceleration is too small when the brake is off. Furthermore, it is avoided that the actual deceleration becomes too large with the passage of time after the start of inertial running and the driver feels uncomfortable.

  In addition, since the target deceleration is determined logarithmically with respect to the vehicle speed, the driver's uncomfortable feeling is further reduced. This is because, in general, humans perceive physical quantities logarithmically, and such logarithmic changes do not give a sense of incongruity.

  The present invention is not limited to the embodiments, examples, and modifications of the present specification, and can be implemented with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in the embodiments described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects described above, replacement or combination can be performed as appropriate. If the technical feature is not described as essential in this specification, it can be deleted as appropriate. For example, the following are exemplified.

  The allowable deceleration by the alternator may be defined in any way. For example, the vehicle speed function may be defined by a function different from the embodiment. FIG. 6 is a graph illustrating the relationship between the allowable deceleration and the vehicle speed (hereinafter referred to as “deceleration-vehicle speed relationship”) in the modified example. As shown in FIG. 6, in Modification 1, the deceleration-vehicle speed relationship is defined by a straight line. In the second modification, the deceleration-vehicle speed relationship is defined by a cubic function that monotonously increases. In addition, the deceleration-vehicle speed relationship may be defined by a curve that is not monotonically increasing (for example, a curve that monotonously decreases), may be defined by a downwardly convex curve, or may be defined by another curve. Good.

Unlike the embodiment, the rate of change of the actual deceleration relative to the vehicle speed (hereinafter simply referred to as “change rate”) may not be constant. 7, 8, and 9 are graphs illustrating the relationship between the change rate and the vehicle speed. FIG. 7 shows a modification example 3, FIG. 8 shows a modification example 4, and FIG. The dimension of the rate of change is (m / s ² ) / (m / s) = s ⁻¹ . As shown in FIGS. 7, 8, and 9, in the case of the embodiment, as described above, the change rate takes a constant value in each of the positive case and the negative case.

  As shown in FIGS. 7, 8, and 9, the rate of change in the modification examples 3, 4, and 5 is zero when the vehicle speed is the speed Vm, and when the value is positive, the change rate is It is common to increase monotonically and to decrease monotonically with increasing vehicle speed when the value is negative. In the case of the modification example 3, the change rate changes linearly. In the case of the modification 4, it changes with a cubic curve. In the case of the modification 5, it changes logarithmically.

  In addition, the rate of change may change in any manner with respect to the vehicle speed. When the vehicle speed is Vm, the rate of change may not be zero, or the absolute value of the rate of change may decrease as the vehicle speed increases.

The rate of change may be a function other than the vehicle speed. For example, it may be a function of the elapsed time since the start of the deceleration control process. Alternatively, the rate of change may be determined by PID control or the like.
The deceleration control process may be continued even after convergence to the target. For example, you may continue until inertial running is complete | finished.
The regeneration device may not be an alternator but may be an assist motor, for example. An assist motor is a motor capable of generating torque to be supplied to drive wheels, auxiliary machines (compressor, etc.), and the like.
The target deceleration may be determined based on pedal operation. For example, different tables may be referred to when the accelerator is off and when the brake is off. These tables may have different characteristics regarding the relationship between the allowable deceleration and the vehicle speed.
The deceleration control described above may be applied to transportation equipment other than automobiles, such as motorcycles and trains.

30 ... Engine ECU
DESCRIPTION OF SYMBOLS 40 ... Alternator 45 ... Belt 50 ... Battery 60 ... Engine 70 ... Transmission 75 ... Drive shaft 80 ... Drive wheel 90 ... Sensor group 91 ... Accelerator stroke sensor 92 ... Brake stroke sensor 93 ... Throttle sensor 94 ... Wheel speed sensor 95 ... Vehicle speed sensor 96 ... Battery sensor

Claims (11)

A regenerative device that regenerates energy associated with traveling of the vehicle as electric power;
A target deceleration determining unit that determines a target value of deceleration when the vehicle is coasting according to a vehicle speed that is the speed of the vehicle;
A vehicle control device comprising: a deceleration control unit that executes deceleration control for controlling the regeneration device to cause the deceleration to approach the determined target value when the vehicle is coasting. The vehicle control device according to claim 1, wherein the vehicle is determined to be coasting when both an accelerator pedal and a brake pedal provided on the vehicle are not depressed. The target deceleration determination unit acquires the allowable deceleration according to the vehicle speed by referring to a predetermined relationship between the allowable deceleration and the vehicle speed, and the acquired allowable deceleration is used as the target deceleration. The vehicle control device according to claim 1, wherein the vehicle control device is determined as follows. The vehicle control device according to any one of claims 1 to 3, wherein the regenerative device is an alternator and is connected to a rotation shaft of an engine mounted on the vehicle. The vehicle control device according to claim 4,
The deceleration control unit
A target negative value determined by taking into account at least one of the rotational speed of an engine mounted on the vehicle, the vehicle weight of the vehicle, and the vehicle speed, as a target value of negative torque generated by regeneration of the alternator. A torque determining unit;
An alternator control unit that brings the negative torque close to the determined target value as control of the regenerative device. A vehicle control device. The vehicle control device according to claim 5, wherein the alternator control unit controls the excitation current flowing through the alternator based on a target value of the negative torque, thereby bringing the negative torque closer to the determined target value. The vehicle control device according to claim 6, wherein the alternator control unit sets an upper limit value of the excitation current as control of the excitation current. The target deceleration determination unit determines the target value so as to monotonically increase with respect to the increase in the vehicle speed in at least a part of the range of the vehicle speed. The vehicle control device described. The deceleration control unit is configured to reduce a rate of change of the deceleration with respect to time when the deceleration is decreased in at least a part of the range of the vehicle speed as compared with a case where the deceleration is increased. The vehicle control device according to claim 8, wherein the deceleration control is executed so that an absolute value becomes large. The target deceleration determining unit determines the target value so that a rate of change of the deceleration with respect to the vehicle speed monotonously decreases with an increase in the vehicle speed in at least a part of the range of the vehicle speed. The vehicle control device according to any one of claims 9 to 9. The deceleration control unit determines a rate of change of the deceleration with respect to time according to the vehicle speed, and executes the deceleration control based on the determined rate of change. The vehicle control device according to item.

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